IL2 and neoplasm: Regarding those formulations that target the tumor site, several studies applied intratumoral or peritumoral injection of nanoparticles loaded with immunostimulatory molecules (such as: IL-12 [154], IL-15 superagonist [155], IL2 and TGF-β [19] among others) with positive outcomes, reporting the initiation of an immune response in tumor-bearing mice.